VATICAN CITY, VATICAN - JANUARY 06: Pope Francis delivers his homily during the Epiphany Mass at St. Peter's Basilica on January 6, 2015 in Vatican City, Vatican. During his homily, the Pope Francis focused on the journey taken by the three wise men, which is celebrated today, and encouraged Catholics to keep a strong faith. (Photo by Franco Origlia/Getty Images)
(2015 Getty Images)

VATICAN CITY (AP) – Pope Francis has decried the "inhuman" conditions facing migrants crossing the U.S.-Mexico border and has encouraged communities there not to judge people by stereotypes but welcome migrants and work to end discrimination.

Francis made the appeal in a letter to a Jesuit priest who helps organize Catholic teens in Nogales, Arizona, to support the Kino Border Initiative, which advocates a more humane solution to migration. The letter was dated Dec. 19 but was made public on Kino's website recently.

"These young people — who have come to learn how to strive against the propagation of stereotypes, from people who only see in immigration a source of illegality, social conflict and violence — can contribute much to show the world a church without borders," Francis wrote.

Rev. Sean Carroll, executive director of Kino Border Initiative, said student were very excited and very touched after receiving the letter from Francis.

"They cross the border every day to serve meals to the migrants," said Carroll, who wrote the cover letter to accompany the teens' messages to the Pope. "I think receiving this letter affirms the work they are doing."

Lucy Howell, a board member of Kino Border Initiative, said the letter was share at a recent board member. "We're ecstatic," Howell said. "We're all touched."

Francis has made migration one of the priorities of his pontificate and will likely raise the issue when he visits the U.S. in September. On Thursday, U.S. officials confirmed he would address Congress on Sept. 24, the first pope to do so.

Francis has said he would have loved to have entered the U.S. via the Mexican border in a "beautiful ... sign of brotherhood and of help to the immigrants." But he said the trip's itinerary was too tight to let him visit the border.

Carroll said a papal visit to the border would be a "transformative event" that might change minds of certain U.S. residents on the issue of immigration. "It would help people reflect deeply on the issue of migration," Carroll said. "I think his visit would have a significant impact."

In his letter, Francis praised migrant initiatives in cities like Nogales "which live daily with the phenomenon of immigration, and the ensuing inhuman situations of all type that it creates." He urged the Kino supporters to "never tire of working to build fraternity and welcome against discrimination and exclusion."

Arizona in 2010 passed tough legislation cracking down on illegal immigration, although much of the law was eventually gutted.